Maintenance functions on digital subscriber lines, such as Metallic Test Access (MTA) testing, commonly involve using external test heads located near communication equipment to be tested. These test heads tend to be expensive, consume valuable real estate, and also require cabling to connect to tested equipment. With distributed equipment architectures or smaller scale remote communication equipment, such as remote Digital Subscriber Line (DSL) Access Multiplexers (DSLAMs) that are deployed to extend the reach of DSL service from a Central Office (CO), the cost of providing a test head for each remote equipment installation compared to the number of ports (customers) served makes an external test head less attractive. Furthermore, the small cabinets that are often used for remote DSLAMs and other equipment have very little physical space to house a test head, and limited power and cooling capabilities.
Efforts have been made to reduce the size of external test heads so that they occupy less space. Test head products which can be accommodated in a communication equipment card slot are also available. However, in this case the test head occupies a card slot that would otherwise be available to deploy a line card for providing service to additional customers. With one less line card slot, the number of customers that can be serviced by a DSLAM or other equipment, as well as the revenue that can be generated using that equipment, are reduced.
Centralized resources such as a test head are also normally connected directly to a specific DSL line. Whenever a DSL port of a DSLAM is connected to a test head or other centralized resource or a test signal is applied to a port or line, for example, that DSL line experiences a disturbance in line conditions. Such a disturbance can result in bit errors or data communication functionality being lost altogether, causing the DSL line to retrain in order to re-establish the lost data link.
Thus, there remains a need for improved subscriber line maintenance techniques.